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Need Help Configuring TCP Optimizer's BDP (RWIN)


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I'm trying to add the TCP Optimizer to my computer before I precede on to the download and running of the LvlLord patch. My problem is that the TCP Optimizer didn't configure the BDP and I don't understand how to solve for the problem, so to speak. Also, is the Bandwidth referred to in BDP...for upload or download and knowing which figure, how do I figure out the MSS.

I bet you need some additional info from me: My max. upload is 384 kilobits and download is 6600.

The info below is from SpeedGuide.net:

This is the shot of my TCP/IP Optimizer:

TCP options string = 020405b401010402

MTU = 1500

MTU is fully optimized for broadband.

MSS = 1460

Maximum useful data in each packet = 1460, which equals MSS.

Default TCP Receive Window (RWIN) = 65535

RWIN Scaling (RFC1323) = 0 bits

Unscaled TCP Receive Window = 65535

Note: TCP 1323 Options need to be enabled for RWIN over 2^16 (65535). Windows 9x might also need the MS Vtcp386 fix.

For optimum performance, consider changing RWIN to a multiple of MSS.

Other RWIN values that might work well with your current MTU/MSS:

513920 (MSS x 44 * scale factor of 8)

256960 (MSS x 44 * scale factor of 4)

128480 (MSS x 44 * scale factor of 2)

64240 (MSS x 44)

bandwidth * delay product (Note this is not a speed test):

Your TCP Window limits you to: 2621.4 kbps (327.675 KBytes/s) @ 200ms

Your TCP Window limits you to: 1048.56 kbps (131.07 KBytes/s) @ 500ms

MTU Discovery (RFC1191) = ON

Time to live left = 117 hops

TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349) = 00100000 (32)

Precedence (priority) = 001 (priority)

Delay = 0 (normal delay)

Throughput = 0 (normal throughput)

Reliability = 0 (normal reliability)

Cost = 0 (normal cost)

Check bit = 0 (correct, 8th checking bit must be zero)

DiffServ (RFC 2474) = CS1 001000 (8) - class 1 (RFC 2474). Similar forwarding behavior to the ToS Precedence field.

This is the Empty BDP window:


I tried to find info on the forums about this and at SpeedGuide.net. SpeedGuide said these figures are very important. They can make or break your downloads because they affect the other servers acknowledge of your request. I assume this means something along the lines of timing out. LOL

Also, according http://forum.utorrent.com/viewtopic.php?id=3912 I need to locate and imput the following info into net.max_halfopen. What is the specified value in TCPIP.sys? Can't patch to 80% until I know which figure in TCPIP is needed.

OK, now it's time for us dive into µTorrent's Advanced Options. I'm going to address only those settings which I believe are going to give you a boost...the rest are better left alone unless you know what you're doing. Remember how I told you to patch your TCPIP.sys file a while ago?

You should patch this to 80% of the value you specified in tcpip.sys (40, if you followed my recommendations). MAKE ABSOLUTELY SURE THIS VALUE IS LOWER THAN THE VALUE YOU SET IN TCPIP.SYS!

Aggressive surfing won't be affected this way. Note: if your modem/router seems to time-out, frequently disconnect etc., you may have to lower the values for the sake of stability.

● net.max_halfopen = *40.

Am I all over or what? :-D


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High half-open limits in µTorrent aren't needed to get good download speeds.

A good "average" RWIN value is:

256960 (MSS x 44 * scale factor of 4)

It may not allow maxed 100 Mbps (or 1 Gbps) LAN transfers, but should still get 60+ Mbps speeds.

And it should be decent for higher-latency, lower-speed internet connections -- such as 10-250 ms latency and 1-10 Mbps download speeds/0.1-10 Mbps upload speeds.

Because of the big difference between LAN and internet, no 1 RWIN value "perfectly" satisfies them all.

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